1. Field of the Invention
The present invention relates to safety bindings for skis adapted to maintain, in a laterally releasable fashion, one of the ends of a boot with respect to a ski. The binding according to the invention can retain either the front of the boot, or the rear, however it is particularly adapted to retain the front.
2. Description of Background and Relevant Information
A safety binding of the type referenced above assures the safety of a skier by responding, through its lateral release, to excessive torsional forces at the level of the leg of the skier. Safety bindings of the conventional type, having a lateral release, have a certain number of disadvantages, particularly when a torsional fall is combined with a frontward fall. In effect, during frontward displacement of the weight of the skier, the bottom of the sole of the boot which is at the level of the front of the foot is applied against the ski with a substantial force directed towards the ski, i.e., downwardly, which serves to create, between the bottom of the sole and the support surface of the ski, a substantial frictional force which opposes the lateral displacement of the boot.
There has long been sought a solution to the problem of safety bindings having a lateral release, so as to provide a binding which maintains the boot without moving during normal skiing in a stable maintenance position of the boot substantially in the longitudinal vertical median plane of the binding, and which is laterally releasable in a sure fashion by reducing to the maximum friction between the sole of the boot and the upper surface of the ski.
It has thus been proposed to glue to the surface of the ski a plate made of an anti-friction material, such as described in French Patent 2 092 844. However, cleats which may be provided under the sole of the boot considerably increase the friction, and accumulated dirt reduces its effectiveness.
To further reduce friction, it has been proposed to insert between the sole of the boot and the upper surface of the ski a moveable support plate adapted to be laterally displaced with the boot The sliding between the moveable plate and the skis is then not adversely affected by dirt or the cleats of the boot.
A first solution, described in document WO 85/03451, consists of utilizing plates affixed to the binding. However, in this first case, if ice forms between the plate and the ski, there is blockage of the binding, or at least a very substantial disturbance of its operation.
A second solution, described in Swiss Patent 490,871, consists of providing a rotating plate, positioned on the upper surface of the ski, and return biased to the central position by a re-centering spring The disadvantage is that, during release of the binding the boot pivots the plate against the energy of its re-centering spring. This energy adds to the energy of the binding, and increases the force which the leg must overcome in order to release from the binding.